, it appears they have pictures of their suspect. our justicecorrespondentpetewilliamshasbeen following the investigation all day. he's in our d.c. newsroom tonight. pete, good evening. >> reporter: brian, good evening. the fbi is pursuing very promising leads. one in particular tonight thanks to the abundance of pictures and videos rounded up in the two days since the bombing. we are getting a close-up look at how the bombs were made. >> guys, guys, guys. no way. >> reporter: the fbi says it is getting exactly what it asked for. pictures from several sources showing someone carrying a heavy backpack or duffel bag and placing it at the spot where one bomb went off. one of the most promising images, they say, comes from a department store surveillance camera high up on a building, able to look down at the crowd. on a day when incorrect news reports of an arrest distracted officials, investigators were working aggressively to discover, find, and interview that person. that's at the scene of the second bombing following the first by about 15 seconds. it's that second spot shown on this pic

at what these men were doing. it's motion video so they can watch their movements. >> allright.petewilliamsin our washington newsroom. no doubt a big step forward in this investigation. lester holt was on the street in boston when the photos went public at that very moment. he witnessed the start of what someone today called the first nationwide electronic crowd-sourced manhunt of the digital era. lester, good evening. >> reporter: brian, good evening. when the crowd watching us glommed onto the fact we were talking about pictures of suspects, the smartphones immediately came out. people started watching that video. one man said to me, i wish i knew them. the president was here just a few hours before we learned of the suspect. whether he knew about them or not is unclear. he had a message for whoever did this. we will find you. bostonians stood for hours in a line ten blocks long for a chance to publically share their sorrow and even their fears. >> i'm sickened by this. we live in such a free country and to have a sense of insecurity. ♪ >> reporter: inside the cathedral, tears

's not going to happen. >> allright,petewilliamstonight,thank you. >>> as authorities search for answers, they are turning more of their attention to a trip the older brother made last year to the russian republics of chechnya and dagestan, both mainly muslim, both with militant separatist movements. tonight nbc's adrian mong is in dagestan in the neighborhood where some of the suspect's family lives. >> reporter: a long way from boston in this remote mountainous city in dagestan in the northern caucasus, relatives and friends of the suspected bombers are in shock over the news that two of their own may have been responsible for the marathon bombings. "i don't believe it but only allah knows," says an uncle of the brothers. tamerlan tsarnaev visited him when he traveled to dagestan last year. in the neighborhood where tamerlan and dzhokhar's father lives, the same sentiment. neighbors here on the street tell us they have a hard time believing what happened because they say the suspect's father is a good man. but the neighbors also say they haven't met the sons. dagestan is the russian fe